TST+RF - add another endian swap test

Added test that asking for a byte-swapped header does result in a header
that looks byte-swapped (with guess_endian).

Some refactoring of code imports.

Author: matthew-brett

nibabel/ecat.py

@@ -9,17 +9,10 @@
 import warnings
 
 import numpy as np
-import copy
-from nibabel.volumeutils import pretty_mapping, endian_codes,native_code,swapped_code
-from nibabel.volumeutils import native_code, swapped_code
-from nibabel.volumeutils import make_dt_codes, allopen
-
-
-from nibabel.spatialimages import SpatialImage, HeaderDataError, HeaderTypeError, ImageDataError
-from nibabel.volumeutils import allopen, array_from_file
-from .fileholders import FileHolderError, copy_file_map
-from .arrayproxy import ArrayProxy
 
+from .volumeutils import (native_code, swapped_code, make_dt_codes,
+                           array_from_file)
+from .spatialimages import SpatialImage, ImageDataError
 
 
 MAINHDRSZ = 502

nibabel/tests/test_ecat.py

@@ -7,12 +7,11 @@
 #
 ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ##
 import os
-from StringIO import StringIO
-import numpy as np
 
-import nibabel
+import numpy as np
 
-from ..ecat import EcatHeader, EcatMlist, EcatSubHeader, EcatImage, native_code
+from ..volumeutils import native_code, swapped_code
+from ..ecat import EcatHeader, EcatMlist, EcatSubHeader, EcatImage
 
 from unittest import TestCase
 
@@ -21,8 +20,9 @@
 
 from numpy.testing import assert_array_equal, assert_array_almost_equal
 
-data_path = os.path.dirname(nibabel.__file__)
-ecat_file = os.path.join(data_path, 'tests','data','tinypet.v')
+from ..testing import data_path
+
+ecat_file = os.path.join(data_path, 'tinypet.v')
 
 class TestEcatHeader(TestCase):
     header_class = EcatHeader
@@ -67,15 +67,21 @@ def test_update(self):
         assert_true(hdr['num_frames'] == 0)
         hdr['num_frames'] = 2
         assert_true(hdr['num_frames'] == 2)
-    
+
     def test_endianness(self):
-        fid = open(ecat_file)
+        # Default constructed header should be native
         native_hdr = self.header_class()
+        assert_true(native_hdr.endianness == native_code)
+        # Swapped constructed header should be swapped
+        swapped_hdr = self.header_class(endianness=swapped_code)
+        assert_true(swapped_hdr.endianness == swapped_code)
+        # Example header is big-endian
+        fid = open(ecat_file)
         file_hdr = native_hdr.from_fileobj(fid)
         fid.close()
-        assert_true(native_hdr.endianness == native_code)
         assert_true(file_hdr.endianness == '>')
-        
+
+
 class TestEcatMlist(TestCase):
     header_class = EcatHeader
     mlist_class = EcatMlist